HD files on SD screen are choppy - how to fix?

[JonTom]

I have a SD tv and I'm trying to play some 720p h.264 videos (.mkv containers) on it smoothly. Audio is always fine, but video has had various levels of success.

First I used the default sageplayer. Video played, but was frequently choppy. I tried vmr9, overlay, fse on/off, 3d accel on/off, no changes. It was choppy in (apparently) the same places when I tried to play the videos on my MPV.

I tried playing the videos locally in wmp/vlc and had the same problems.

Then I tried COREAVC. I got it installed and wmp/vlc gave me perfect playback. In sage, though, I got a black screen (although the timebar moved and the audio continued to be fine). I set sage to use dshow and experimented with overlay, etc, with no success.

I tried Cyberlink/PowerDVD. Again, wmp/vlc perfect. Sage is closer now - sometimes I get the black screen, but more often I get audio for a few seconds, then the video 'turns on' (in sync). This is not 100% reliable, however. Also, sometimes sage gets minimized when I hit play (go to windows desktop) - is this because an external player is being called?

I haven't tried the MVP since installing the new codecs because I assume that the codecs won't affect it? Presumably the transcoding from 720p for either local playback (using sageplayer) or MVP playback is just a bit too much for the computer?

I'm using an AMD X2 4000+, with an onboard ati 1200 series video card from the gigabyte mobo (GA-MA69VM-S2), and 1gb of RAM (one stick, not dual channel). Windows XP pro. Sage is in service mode, so locally on the server I'm using the client, which I believe isn't working with CoreAVC - correct?

What's the best way to attack this situation? Ideally, I'd like to have silky smooth playback locally and on the MVP, but I could settle for only local playback. Do I need more RAM? I didn't think I needed a burly videocard since I don't output HD to the screen, but maybe that's incorrect? The lack of success on the MVP, however, leads me to think that the transcoding is too much for the CPU.

What to do?

edit: I'm using the latest ati drivers from the gigabyte website, but I see that there is a newer version available on the ati site (also an Avivo suite). I suppose I should try these? Do I need the drivers AND the Avivo? Avivo enables hardware transcoding - maybe that's what I need to update/enable?

[JonTom]

bump:

i installed the new ati drivers, no better. in fact, i can't seem to get sageplayer working at all now. dshow is not very reliably working either.

is anyone playing 720p h.264 video successfully on a SD tv?